If you setup user namespace, the child processes will inherit that namespace. The difference is that plan9 is fully built on this idea and isn't multi-user, on linux you have to opt-in to this. It's very useful and underused (mostly used by containers). I wanted to ship my AWS lambdas this way, but sadly AWS lambdas don't allow user namespaces.

https://github.com/aws/aws-lambda-base-images/issues/143